Add WCAG Alt Text to Every Image with One API Call

#a11y #webdev #api

If your site has images without alt text, you have two problems:

Screen readers can't describe them to visually impaired users
You might get sued -- ADA lawsuits over web accessibility hit record numbers in 2025

Manually writing alt text for hundreds of images is tedious. So I built an API that does it with one call per image.

The API

Send an image URL, get WCAG 2.1 compliant alt text back:

curl -X POST https://api.origrid.io/v1/alt/generate \
  -H "Content-Type: application/json" \
  -d '{"image_url": "https://picsum.photos/id/42/800/600"}'

Response:

{
  "alt_text": "Two teal coffee cups on saucers and a smartphone on a rustic wooden table in a cafe",
  "alt_text_length": 84,
  "wcag_compliant": true
}

That's it. No complex setup, no image upload, no training. Send a URL, get alt text.

What makes it WCAG compliant

The API follows WCAG 2.1 Success Criterion 1.1.1:

Max 125 characters -- screen readers handle short alt text better
Describes content, not decoration -- "sunset over beach" not "beautiful photo"
Never starts with "Image of" or "Photo of" -- screen readers already announce it's an image
Specific -- mentions subjects, actions, colors, and setting

The wcag_compliant boolean in the response tells you programmatically whether the generated text meets the criteria.

Real examples

Image	Generated alt text
Beach sunset	`Golden sunset over sandy beach with turquoise waters and palm tree silhouettes`
Coffee shop	`Two teal coffee cups on saucers and a smartphone on a rustic wooden table in a cafe`
Dog portrait	`A black labrador puppy sits on a wooden floor, looking up with big dark eyes`
Mountain landscape	`Mountain lake surrounded by pine trees with snow-capped peaks reflected in calm blue water`

All under 125 characters, all descriptive, all screen-reader friendly.

Bulk processing with Python

Here's how to add alt text to every image on a page:

import requests
from bs4 import BeautifulSoup

RAPIDAPI_KEY = "your_key"
HEADERS = {
    "X-RapidAPI-Key": RAPIDAPI_KEY,
    "Content-Type": "application/json"
}

def get_alt_text(image_url):
    resp = requests.post(
        "https://origrid-alt-text.p.rapidapi.com/v1/alt/generate",
        headers=HEADERS,
        json={"image_url": image_url}
    )
    return resp.json()["alt_text"]

# Fetch page and find images without alt text
page = requests.get("https://yoursite.com/page")
soup = BeautifulSoup(page.text, "html.parser")

for img in soup.find_all("img"):
    if not img.get("alt"):
        alt = get_alt_text(img["src"])
        img["alt"] = alt
        print(f"Added: {alt}")

# Save the updated HTML
with open("updated_page.html", "w") as f:
    f.write(str(soup))

Why not use ChatGPT directly?

You could, but:

ChatGPT doesn't enforce 125 char limit -- you'd need to prompt-engineer and validate
No wcag_compliant flag -- you'd build your own validation
API integration is messy -- ChatGPT's API isn't designed for single-purpose endpoints
Cost -- GPT-4 vision is expensive for bulk image processing

Origrid Alt Text is a purpose-built endpoint. One call, one response, validated output.

Try it

Origrid Alt Text on RapidAPI -- free tier, no setup.

Or test directly:

# Try with any public image URL
curl -X POST https://api.origrid.io/v1/alt/generate \
  -H "Content-Type: application/json" \
  -d '{"image_url": "https://picsum.photos/id/237/800/600"}'